Automated data storage libraries provide a means for storing large quantities of data in data storage media that are not permanently mounted in data storage drives, and that are stored in a readily available form on storage shelves. One or more accessors retrieve selected data storage media from storage shelves and provide them to data storage drives.
Typically, data stored on data storage media of an automated data storage library, once requested, is needed quickly. In addition, as customer expectations move toward a concept of continuous availability, such as the well known “24×7×365” availability, it is increasingly important that equipment malfunction does not disrupt customer operations.
Traditionally, redundancy has been used to mitigate the effects of equipment malfunction. In the event a device, such as an accessor, fails, the ability to activate and operate a reserve accessor provides failover protection and therefore, improves the availability of the library.
Resource redundancy, however, could also be used to improve the overall performance of the automated data storage library in the absence of equipment failure. For example, the ability to simultaneously operate two accessors during heavy data access periods, while operating a single accessor at other times, would provide optimal system performance at reduced operating and purchase costs.
What is needed is an apparatus and method that allows a data storage system user to select varying levels of accessor availability on request. Applicants' apparatus and method provide at least one redundant gripper and/or accessor which can be partially, or completely, activated by the user.